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sportee
Samba Member
Joined: October 18, 2005
Posts: 102
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 Posted: Thu Nov 03, 2005 8:55 am Post subject: Porsche heads on VW |
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you've probably seen a few of my questions about different engine cominations... im trying to decide what type of engine to build for a vintage racer.
ive got a 36 hp engie with okrasa crank and im trying to decide whether to go with the ultra rare okrasa heads (that would need to be cut for the rare 82mm mahle's) or a pair of porsche heads. (the hemispherical combustion chamber seems to be a better design to me than the okrasa chamber)
has anyone out there put a pair of porsche heads on a 36 hp VW?
Which heads would work? |
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james caste
Samba Member
Joined: December 08, 2003
Posts: 228
Location: Rockland,NY
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| Posted: Thu Nov 03, 2005 9:39 am Post subject: |
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The 911 cylinder head was an SOHC valvetrain design and cannot be used on a vw without extreme modification, as you would need to develop a cam shaft for a four cylinder engine and chain drive system to drive it. I have seen it done in pictures though. The 365 head I'm sure could be put on in some way, but what would be the point? They're pretty much the same and have more restirctive square exhaust ports anyway. Hope this helps.
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CasteSystms Performance
68' Beetle (2110cc)
62' Beetle Vert (1776cc)
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Glenn 
Mr. 010
Joined: December 25, 2001
Posts: 76940
Location: Sneaking up behind you
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| Posted: Thu Nov 03, 2005 9:42 am Post subject: |
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I think he only ment the 356 head.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
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Jake Raby
Samba Member
Joined: August 23, 2003
Posts: 7433
Location: Aircooled Heaven USA
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| Posted: Thu Nov 03, 2005 10:53 am Post subject: |
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The bore spacing and register locations are not compatible... AND the 356 heads are a totally different animal on the breating side of things, even if you get them to physically fit.. the 356 head is basically a head with 100% I/E and depends upon its cam to split the flow margins, this is typical of 50s era performance engines.. Finding the right cam to make them work correctly, especially for coming off the corners better will be a project all in it's own.
THE 356 HEAD DOES NOT HAVE A RESTRICTIVE EXHAUST PORT!!!! That port, regardless of shape will flow 170 CFM with no port work!!! It will sustain a 180 HP combination without touching the heads on the exhaust side at all...
Here is a link to my latest 356/912 project- It'll be showcased in Excellence magazine in mid 2006. It's destined for 200 horses from 1900ccs.
http://www.aircooledtechnology.com/r_d_modern_912.htm
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Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell" |
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